(function(){
    var oViewport = document.getElementById('viewport');
    var phoneWidth = parseInt(window.screen.width);
    var phoneScale = phoneWidth/640;
    var ua = navigator.userAgent;

    if(/Android (\d+\.\d+)/.test(ua)){
        var version = parseFloat(RegExp.$1);
        if(version>2.3){
            oViewport.setAttribute('content','width=640, minimum-scale = '+ phoneScale +', maximum-scale = '+ phoneScale +', target-densitydpi=device-dpi')
        }else{
            oViewport.setAttribute('content','width=640, target-densitydpi=device-dpi');
        }
    } else {
        oViewport.setAttribute('content', 'width=640, user-scalable=no, target-densitydpi=device-dpi');
    }

    window.onload = function(){
        document.body.addEventListener('touchstart', function (){});
    }
})();